上海地区土壤碳汇功能评估

Evaluation of Soil Carbon Sinks in Shanghai

利用上海市第二次土壤普查资料,2004年—2005年上海耕地地力调查资料,以及2009年实地调查采样、实验分析获得的数据,研究了3个时期上海土壤有机碳的变化特征。结果表明,20多年来上海土壤有机碳平均含量没有明显变化,土壤有机碳库逐渐减小,从而使得上海城市化过程中土壤成为一种碳源,而不是碳汇。城市郊区以扩大蔬菜、果树、苗木种植为特征的旱地作物种植方式代替水稻田,是城市化影响土地利用类型变化的明显特征,而水稻田土壤有机碳含量高于林地、菜地。种植结构的变化对土壤有机碳含量有重要影响,同时,耕作制度、耕作方式、施肥等农业管理方式也有一定影响。虽然园林绿地得到快速发展,但没有弥补城市化过程导致农田面积减少带来的有机碳损失。

With the rapid development of urbanization,the land use changes had been intensified,which af- fected soil organic carbon stock. To explore how urbanization effected on soil carbon sequestration,taking Shang- hai as example, which was the most rapid development of urbanization in China, the second soil survey data of Shanghai, the farmland survey data in Shanghai between the year 2004 and the year 2005 ,and the field sampling in the year 2009 were used to analyze the variation characters of soil organic carbon. It was found that the average content of soil organic carbon did not change significantly,but the soil organic carbon pool decreased. Thereby, the soil worked as a kind of carbon source,rather than carbon. It was the obvious features of the urbanization to land use changes that the planting structure changed from rice fields to dry land erops for planting vegetable, fruit, and seedlings in some suburban areas. While the organic carbon contents of paddy soil were higher than that of forest and vegetable garden, so planting structure changes had a major impact on soil organic carbon content. Meanwhile ,farming systems ,tillage pattern ,fertilizer and other agricultural management practices also influenced the changes of soil organic carbon content. As far as the urban green space,it did not make up the loss of soil or- ganic carbon lead by urbanization.